When a Kotlin identifiers contains non-ES5 chars, JS BE
either reports error (for published declarations) or mangles name
(for non-published ones). The old approach relied on wrong
assuption that Java identifier = ES identifier.
However, that's not true. This commit introduces functions that
check identifiers according to ES5.1 spec rather than
using Character.isIdentifierStart[Part]
See KT-17476
Friend modules should be provided using the -Xfriend-modules flag
in the same format as -libraries. No manual configuration required for
JPS, Gradle and Maven plugins.
Friend modules could be switched off using the -Xfriend-modules-disabled
flag. Doing that will
* prevent internal declarations from being exported,
* values provided by -Xfriend-modules ignored,
* raise a compilation error on attemps to use internal declarations from other modules
Fixes #KT-15135 and #KT-16568.
Anton Bannykh